In response to multiple requests, today’s column will be another “medical myth or fact?”

- The menstrual periods of women who live together become synchronized:

Since research in 1971 and several studies thereafter noted that the periods of women who live together become synchronized, there has been speculation into why this may occur; some studies have looked at pheromone signals as a possible explanation.

However, some authorities question whether this is even true, noting it may just be statistical fluctuation; ‘synchronization’ is usually defined as within several days and the studies demonstrating this phenomenon have been small in size. Even the research showing that synchronization does occur notes that it is not an absolute phenomenon; it does not occur for all women living together. Overall, count this one as true; maybe.

- You should wait at least one hour after eating before going swimming or you might die:

It may be that it is more likely to have some uncomfortable abdominal cramping if you swim or exercise shortly after eating, but there is no evidence that it is actually dangerous to do so. So this one is not t

- The tongue is the strongest muscle in the body:

What is meant by “strongest?” There are three different kinds of muscles in the human body; skeletal muscle, smooth muscle and cardiac muscle, and they each have their own “strengths.”

Cardiac muscle would likely win as “most reliable and hardest working;” the heart beats about once per second and will do so up to 3 billion times over someone’s lifetime, doing the most total work of any muscle in the body. If the amount of pressure exerted per weight of muscle is what strongest means then the chewing muscles (masseter muscles) are the strongest, able to apply a pressure of over 50 pounds on the incisors and up to 200 pounds on the molars, although this force is created utilizing mechanical advantage to manipulate the jaw bones.

If strongest means the maximum force generated per weight, then the muscles of the uterus (which push the baby out during child birth) would be the strongest.

If strongest means overall largest force exerted, then the gluteus maximus (the backside muscles, the largest muscles in the body which allow us to stand up straight, walk and climb stairs) would win.

If strongest means able to pull the hardest, then the calf muscles, which allow us to walk, run and jump, are the strongest.

If strongest means able to lift the highest multiple of its own weight, then the tongue wins; it can lift over 80 times its own weight (although the tongue is really eight different muscles acting in concert). So, this one is, “it depends.”

- We only use 10 percent of our brains:

Page 2 of 2 - MRI and PET scans do not demonstrate any significant portions of the brain that are not utilized; in fact all areas of the brain “light up” when these tests are done. Of course, we could delve further, specifically into how efficiently we are using our brains, but that is a different story. So this one is not true.

- Teething in infants can cause fever:

Teething does not cause a high fever (over 101 degrees Fahrenheit), but it does cause irritability, and this may make the baby feel warm and cause parental concern; it may also cause slight elevation in temperature (under 101). So this is true for a mild elevated temperature, but not for a true fever.

- Too much coffee can keep you awake:

Caffeine acts as a stimulant, reaching its peak blood levels about an hour after ingestion and typically having effects for about four to six hours. The “dose” required to affect someone is variable, but is usually equivalent to about two to four cups of coffee; people who drink a lot of caffeine build up tolerance, so the same “dose” does not affect them as much. So this one is true; I am guessing most people knew that.

However, there is another claim about coffee; that it will “sober you up.” Once in the blood stream, alcohol must be metabolized so it can be eliminated from the body. Although caffeine may stimulate someone who is drunk so they seem to be less drunk, this is not the case; they may be a bit more alert, but they are no less inebriated. So this “benefit” of caffeine is a myth.